security/keys/proc.c

   1 /* procfs files for key database enumeration
   2  *
   3  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sched.h>
  15 #include <linux/fs.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/seq_file.h>
  18 #include <asm/errno.h>
  19 #include "internal.h"
  20
  21 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
  22 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
  23 static void proc_keys_stop(struct seq_file *p, void *v);
  24 static int proc_keys_show(struct seq_file *m, void *v);
  25
  26 static const struct seq_operations proc_keys_ops = {
  27         .start  = proc_keys_start,
  28         .next   = proc_keys_next,
  29         .stop   = proc_keys_stop,
  30         .show   = proc_keys_show,
  31 };
  32
  33 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
  34 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
  35 static void proc_key_users_stop(struct seq_file *p, void *v);
  36 static int proc_key_users_show(struct seq_file *m, void *v);
  37
  38 static const struct seq_operations proc_key_users_ops = {
  39         .start  = proc_key_users_start,
  40         .next   = proc_key_users_next,
  41         .stop   = proc_key_users_stop,
  42         .show   = proc_key_users_show,
  43 };
  44
  45 /*
  46  * Declare the /proc files.
  47  */
  48 static int __init key_proc_init(void)
  49 {
  50         struct proc_dir_entry *p;
  51
  52         p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
  53         if (!p)
  54                 panic("Cannot create /proc/keys\n");
  55
  56         p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
  57         if (!p)
  58                 panic("Cannot create /proc/key-users\n");
  59
  60         return 0;
  61 }
  62
  63 __initcall(key_proc_init);
  64
  65 /*
  66  * Implement "/proc/keys" to provide a list of the keys on the system that
  67  * grant View permission to the caller.
  68  */
  69 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
  70 {
  71         struct user_namespace *user_ns = seq_user_ns(p);
  72
  73         n = rb_next(n);
  74         while (n) {
  75                 struct key *key = rb_entry(n, struct key, serial_node);
  76                 if (kuid_has_mapping(user_ns, key->user->uid))
  77                         break;
  78                 n = rb_next(n);
  79         }
  80         return n;
  81 }
  82
  83 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
  84 {
  85         struct user_namespace *user_ns = seq_user_ns(p);
  86         struct rb_node *n = key_serial_tree.rb_node;
  87         struct key *minkey = NULL;
  88
  89         while (n) {
  90                 struct key *key = rb_entry(n, struct key, serial_node);
  91                 if (id < key->serial) {
  92                         if (!minkey || minkey->serial > key->serial)
  93                                 minkey = key;
  94                         n = n->rb_left;
  95                 } else if (id > key->serial) {
  96                         n = n->rb_right;
  97                 } else {
  98                         minkey = key;
  99                         break;
 100                 }
 101                 key = NULL;
 102         }
 103
 104         if (!minkey)
 105                 return NULL;
 106
 107         for (;;) {
 108                 if (kuid_has_mapping(user_ns, minkey->user->uid))
 109                         return minkey;
 110                 n = rb_next(&minkey->serial_node);
 111                 if (!n)
 112                         return NULL;
 113                 minkey = rb_entry(n, struct key, serial_node);
 114         }
 115 }
 116
 117 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
 118         __acquires(key_serial_lock)
 119 {
 120         key_serial_t pos = *_pos;
 121         struct key *key;
 122
 123         spin_lock(&key_serial_lock);
 124
 125         if (*_pos > INT_MAX)
 126                 return NULL;
 127         key = find_ge_key(p, pos);
 128         if (!key)
 129                 return NULL;
 130         *_pos = key->serial;
 131         return &key->serial_node;
 132 }
 133
 134 static inline key_serial_t key_node_serial(struct rb_node *n)
 135 {
 136         struct key *key = rb_entry(n, struct key, serial_node);
 137         return key->serial;
 138 }
 139
 140 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
 141 {
 142         struct rb_node *n;
 143
 144         n = key_serial_next(p, v);
 145         if (n)
 146                 *_pos = key_node_serial(n);
 147         return n;
 148 }
 149
 150 static void proc_keys_stop(struct seq_file *p, void *v)
 151         __releases(key_serial_lock)
 152 {
 153         spin_unlock(&key_serial_lock);
 154 }
 155
 156 static int proc_keys_show(struct seq_file *m, void *v)
 157 {
 158         struct rb_node *_p = v;
 159         struct key *key = rb_entry(_p, struct key, serial_node);
 160         unsigned long flags;
 161         key_ref_t key_ref, skey_ref;
 162         time64_t now, expiry;
 163         char xbuf[16];
 164         short state;
 165         u64 timo;
 166         int rc;
 167
 168         struct keyring_search_context ctx = {
 169                 .index_key              = key->index_key,
 170                 .cred                   = m->file->f_cred,
 171                 .match_data.cmp         = lookup_user_key_possessed,
 172                 .match_data.raw_data    = key,
 173                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
 174                 .flags                  = KEYRING_SEARCH_NO_STATE_CHECK,
 175         };
 176
 177         key_ref = make_key_ref(key, 0);
 178
 179         /* determine if the key is possessed by this process (a test we can
 180          * skip if the key does not indicate the possessor can view it
 181          */
 182         if (key->perm & KEY_POS_VIEW) {
 183                 skey_ref = search_my_process_keyrings(&ctx);
 184                 if (!IS_ERR(skey_ref)) {
 185                         key_ref_put(skey_ref);
 186                         key_ref = make_key_ref(key, 1);
 187                 }
 188         }
 189
 190         /* check whether the current task is allowed to view the key */
 191         rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
 192         if (rc < 0)
 193                 return 0;
 194
 195         now = ktime_get_real_seconds();
 196
 197         rcu_read_lock();
 198
 199         /* come up with a suitable timeout value */
 200         expiry = READ_ONCE(key->expiry);
 201         if (expiry == 0) {
 202                 memcpy(xbuf, "perm", 5);
 203         } else if (now >= expiry) {
 204                 memcpy(xbuf, "expd", 5);
 205         } else {
 206                 timo = expiry - now;
 207
 208                 if (timo < 60)
 209                         sprintf(xbuf, "%llus", timo);
 210                 else if (timo < 60*60)
 211                         sprintf(xbuf, "%llum", div_u64(timo, 60));
 212                 else if (timo < 60*60*24)
 213                         sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
 214                 else if (timo < 60*60*24*7)
 215                         sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
 216                 else
 217                         sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
 218         }
 219
 220         state = key_read_state(key);
 221
 222 #define showflag(FLAGS, LETTER, FLAG) \
 223         ((FLAGS & (1 << FLAG)) ? LETTER : '-')
 224
 225         flags = READ_ONCE(key->flags);
 226         seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
 227                    key->serial,
 228                    state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
 229                    showflag(flags, 'R', KEY_FLAG_REVOKED),
 230                    showflag(flags, 'D', KEY_FLAG_DEAD),
 231                    showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
 232                    showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
 233                    state < 0 ? 'N' : '-',
 234                    showflag(flags, 'i', KEY_FLAG_INVALIDATED),
 235                    refcount_read(&key->usage),
 236                    xbuf,
 237                    key->perm,
 238                    from_kuid_munged(seq_user_ns(m), key->uid),
 239                    from_kgid_munged(seq_user_ns(m), key->gid),
 240                    key->type->name);
 241
 242 #undef showflag
 243
 244         if (key->type->describe)
 245                 key->type->describe(key, m);
 246         seq_putc(m, '\n');
 247
 248         rcu_read_unlock();
 249         return 0;
 250 }
 251
 252 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 253 {
 254         while (n) {
 255                 struct key_user *user = rb_entry(n, struct key_user, node);
 256                 if (kuid_has_mapping(user_ns, user->uid))
 257                         break;
 258                 n = rb_next(n);
 259         }
 260         return n;
 261 }
 262
 263 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
 264 {
 265         return __key_user_next(user_ns, rb_next(n));
 266 }
 267
 268 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
 269 {
 270         struct rb_node *n = rb_first(r);
 271         return __key_user_next(user_ns, n);
 272 }
 273
 274 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
 275         __acquires(key_user_lock)
 276 {
 277         struct rb_node *_p;
 278         loff_t pos = *_pos;
 279
 280         spin_lock(&key_user_lock);
 281
 282         _p = key_user_first(seq_user_ns(p), &key_user_tree);
 283         while (pos > 0 && _p) {
 284                 pos--;
 285                 _p = key_user_next(seq_user_ns(p), _p);
 286         }
 287
 288         return _p;
 289 }
 290
 291 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
 292 {
 293         (*_pos)++;
 294         return key_user_next(seq_user_ns(p), (struct rb_node *)v);
 295 }
 296
 297 static void proc_key_users_stop(struct seq_file *p, void *v)
 298         __releases(key_user_lock)
 299 {
 300         spin_unlock(&key_user_lock);
 301 }
 302
 303 static int proc_key_users_show(struct seq_file *m, void *v)
 304 {
 305         struct rb_node *_p = v;
 306         struct key_user *user = rb_entry(_p, struct key_user, node);
 307         unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 308                 key_quota_root_maxkeys : key_quota_maxkeys;
 309         unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
 310                 key_quota_root_maxbytes : key_quota_maxbytes;
 311
 312         seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
 313                    from_kuid_munged(seq_user_ns(m), user->uid),
 314                    refcount_read(&user->usage),
 315                    atomic_read(&user->nkeys),
 316                    atomic_read(&user->nikeys),
 317                    user->qnkeys,
 318                    maxkeys,
 319                    user->qnbytes,
 320                    maxbytes);
 321
 322         return 0;
 323 }